The Zvezda Kh-66 and Kh-23
Grom (Russian: ะฅ-23
ะัะพะผ 'Thunder'; NATO:AS-7 'Kerry')
are a family of early Soviet tactical air-to-surface missiles with a
range of 10 km. They were intended for use against small
ground or naval targets. The Kh-66 was effectively a heavy-warhead,
beam-riding version of the K-8 (AA-3 'Anab') air-to-air missile
rushed into service in Vietnam in 1968. The Kh-23 was an improved
Kh-66 with command-guidance, similar to the AGM-12
Bullpup.

Contents

Development

Work on air-to-air missiles had started at the Kaliningrad
Engineering Plant (then known as Plant #455, and later merged into
Zvezda-Strela) in 1955.[1]
This had resulted in the Kaliningrad K-5 (AA-1 'Alkali') family
of beam-guided missiles, including the K-51 (RS-2-US) carried by
the Su-9
'Fishpot'. OKB-4 Molniya (later Vympel NPO) under Matus Bisnovat would go on to produce
missiles such as the Bisnovat R-40 (AA-6 'Acrid').[1]
Meanwhile in 1963 the RS-2-US was tested as an air-to-surface
missile.[1]
It was concluded that the small warhead and inaccurate guidance
made such an application "pointless".[1]

However, in 1965 North Vietnam requested an air-to-surface
missile from the Soviet government;[1]
the AGM-12
Bullpup had entered service with the US Air Force before the
start of the Vietnam
War. In April 1965 OKB-134 (later NPO Vympel) started work on
this missile under the project name Kh-23, but they had problems
developing a guidance system that would work with existing
aircraft.[3]
As a result Yurii N. Korolyov came up with his own proposals based
on the earlier experiments with the RS-2-US. A design bureau to
develop the RS-2-US for surface targets was set up under Korolyov
by decree #100 of 12 March 1966 of the Ministry of the Aircraft
Industry;[1]
this bureau would become the Zvezda OKB in 1976.[4]

The resulting weapon used the body of a K-8 (AA-3
'Anab') K-5 guidance and propulsion systems but increased the
warhead from 13 kg (29 lb) to 100 kg
(220 lb).[5]
This had the big advantage of allowing the new weapon to be fitted
to any aircraft capable of firing the K-5.[3]
Design began in 1966,[4]
so the project was known as Kh-66 or
Izdeliye 66 ('Article 66'). The Kh-66 was a
beam-riding weapon that was tested on a MiG-21PFM[4]
and entered production in 1968 for that aircraft. The Kh-66 was
only an interim solution as it required the launch aircraft to dive
towards the target to maintain lock on the target. Flight testing
of the Kh-66 began in 1967[1]
and it entered service on 20 June 1968.[1]

Meanwhile Korolyov took over work on the Kh-23
project intended for carriage on the Soviet Union's new Mig-23.[3]
The Kh-23 became a development of the Kh-66 design with an improved
propellant and new Delta-R1M guidance system.[3]
The main practical difference was that it was a line-of-sight
radio-command weapon similar to the Bullpup, allowing it to be
fired in level flight (unlike the Kh-66). The first ten were tested
in early 1968,[3]
but significant delays were caused by problems with unreliable
guidance which was eventually traced to the smoke generator which
interfered with the antenna.[3]
Once the receiver had been moved to a tail extension,[3]
the government tested the missile on the MiG-23 and MiG-23B between
20 March 1970 and 3 October 1973.[1]
and it entered service in 1973.[2] A
laser-guided version of the Kh-23, the Kh-25, became the basis for
the AS-10 'Karen' family of missiles.[1]
Technology from these was 'backported' to the Kh-23 to create the
Kh-23M in 1974.[2]

The Kh-23 was later licenced for local production in both
Romania and Yugoslavia.[3]
In 1977 a dummy Kh-23 was fired from a Ka-252TB helicopter,[1]
the prototype of the Kamov Ka-29TB 'Helix-B' assault
transport.

Design

The Kh-66 used the airframe of the Kaliningrad K-8 (AA-3 'Anab')
air-to-air missile, with the nozzle split to make room for the
antenna of the beam-riding guidance system of the Kaliningrad K-5
(AA-1 'Alkali').[3]
It has cruciform control fins on the nose, and four clipped-tip
delta-wings at the rear with elevators for control.

Operational
history

The Kh-66 entered production for the MiG-21 in 1968, and the
Kh-23 was certified for the MiG-23 'Flogger' in 1973.

Variants

Serbian GROM-B missile, based on Kh-23

Kh-66 - the original beam-riding missile based
on the K-8

Kh-23 (Izdeliye 68)[4] -
First command-guidance version with improved propellant